House price index methodology

Nationwide house prices are mix adjusted - i.e. we track a representative house price over time rather than the simple average price. We do not use the simple average price because it is too easily influenced by a change in the mix (i.e. proportion of different property types, locations etc) of houses.

Although it remains similar to the Halifax method we substantially updated our system in 1993 following the publication of the 1991 census data. These improvements mean that our system is more robust to lower sample sizes because it better identifies and tracks our representative house price.

To find out how we create our House Price Index, view the full methodology (PDF).

Questions and Answers

House price information is derived from Nationwide lending data for properties at the post survey approval stage.

We have the longest unbroken run of house price data - it stretches back to 1952 on a quarterly basis and 1991 on a monthly basis

No. The whole point of mix adjusting prices is to remove any bias that the Nationwide mortgage data may exhibit whether that be the type of property we lent on or its location or indeed any one of the other characteristics we use to identify our representative house.

Nationwide has sufficient sample size to produce a representative house price series. N.B. Net lending figures quoted at our half yearly and annual results are not a guide to our sample size. Sample size is based on the number of new loans we write i.e. the amount of gross lending for house purchase

Over long periods the Halifax and Nationwide series of house prices tend to follow similar patterns. This stems from both Nationwide and Halifax using similar statistical techniques to produce their prices. Our average price differs because the representative property we track is different in make up to that of Halifax.

We seasonally adjust our prices because the time of year has some influence. Winter months tend to see weaker price rises and spring/summer see higher increases all other things being equal

Click the what region link on the HPI calculator to use our postcode search. Alternatively, view a list of all local authorities and their associated house price region (.xls)

The monthly and quarterly indices are published within a few working days either side of the last day of the month or quarter.

Should you wish to make a complaint about the Nationwide House Price Indices, please use the Nationwide Complaint Form, selecting “A recent communication from Nationwide” in the What’s your complaint about box.

Did you know...

Nationwide have been publishing house price data since 1952.

Legal Information

The Nationwide House Price Indices are prepared from information that we believe is collated with care, but no representation is made as to their accuracy or completeness. We reserve the right to vary our methodology and to edit or discontinue the indices at any time, for regulatory or other reasons.

Persons seeking to place reliance on the Indices for any purpose whatsoever do so at their own risk and should be aware that various factors, including external factors beyond Nationwide Building Society’s control might necessitate material changes to the Indices.

The Nationwide House Price Indices may not be used for commercial purposes including as a reference for: 1) determining the interest payable, or other sums due, under loan agreements or other contracts relating to investments 2) determining the price at which investments may be bought or sold or the value of investments or 3) measuring the performance of investments.

Nationwide Building Society is the owner of the trade mark “Nationwide” and all copyright and other rights in the Nationwide House Price Indices.

The application of the IOSCO Principles on financial benchmarks to the NHPI is more fully set out in our statement regarding IOSCO Principles. Nationwide considers that its arrangements for administration of the NHPI comply with the IOSCO Principles in a proportionate manner having regard to the nature of the index.

Commentary and other materials posted on our website are not intended to amount to advice on which reliance should be placed or an offer to sell or solicit the purchase by you of any products or services that we provide. We therefore do not accept any liability or responsibility arising from any reliance placed on such materials by any visitor to our website, or by anyone who may be informed of any of its contents.